Nephrology Practice Questions

Q: A 3-month-old infant presents with bilateral medullary nephrocalcinosis. All of the following can cause medullary nephrocalcinosis except:

ARPKD. ***Correct: ARPKD (Autosomal Recessive Polycystic Kidney Disease)*** - **ARPKD** is characterized by bilateral enlarged kidneys with numerous cysts originating from the collecting ducts - Primarily presents with **renal failure, hypertension, and hepatic fibrosis** - **NOT typically associated with medullary nephrocalcinosis** - the cystic changes do not lead to calcium deposition - This is the correct answer as it does NOT cause medullary nephrocalcinosis *Incorrect: Hyperoxaluria* - **Primary hyperoxaluria** is a well-established cause of medullary nephrocalcinosis - Leads to **calcium oxalate crystal deposition** in the renal medulla and tubules - Increased oxalate excretion binds with calcium to form insoluble crystals that deposit in the kidney parenchyma *Incorrect: Bartter's syndrome* - Renal salt-wasting disorder causing polyuria, polydipsia, and electrolyte imbalances - Leads to **hypercalciuria** which causes calcium deposition in the renal medulla - Well-recognized cause of medullary nephrocalcinosis in infants and children *Incorrect: Prolonged use of furosemide* - Loop diuretic that inhibits the Na-K-2Cl cotransporter in the thick ascending limb - Causes increased **urinary calcium excretion (hypercalciuria)** - Calcium precipitates in the renal medulla, leading to nephrocalcinosis - Particularly relevant in premature infants receiving prolonged furosemide therapy

Q: A 4-year-old girl presented with urinary infection caused by E. coli, pus cells in the urine, dilation of the left ureter with hydroureter, and a micturating cystourethrogram showing a filling defect in the bladder. What is the likely diagnosis?

Ureterocele (a cystic lesion in the ureter). ***Ureterocele (a cystic lesion in the ureter)*** - A **ureterocele** is a congenital malformation where the **distal ureter balloons into the bladder**, creating a filling defect on a micturating cystourethrogram (MCUG). - Its presence can lead to **obstruction** and **stasis**, causing recurrent **urinary tract infections (UTIs)**, **hydroureter**, and **hydronephrosis**. *Sacrococcygeal teratoma (a congenital tumor)* - A **sacrococcygeal teratoma** is a tumor typically found at the base of the spine and is usually **palpable externally** or identified prenatally. - While it can cause urinary symptoms due to compression, it would not directly present as a **filling defect within the bladder** on an MCUG. *Posterior urethral valves (a condition in males)* - **Posterior urethral valves** are obstructive membranes found in the **male urethra**, almost exclusively affecting boys. - This condition is unlikely in a 4-year-old girl and typically causes global bladder and upper tract dilation rather than a discrete filling defect from a ureteral anomaly. *Vesicoureteral reflux (urine backflow into the ureters)* - **Vesicoureteral reflux (VUR)** is the **abnormal backflow of urine from the bladder into the ureters** and often presents with UTIs and hydroureter. - However, VUR itself does not create a **filling defect in the bladder** on an MCUG; rather, the contrast would be seen flowing up the ureter.

Question 1

A 3-month-old infant presents with bilateral medullary nephrocalcinosis. All of the following can cause medullary nephrocalcinosis except:

Accepted Answer

ARPKD

Answer

Bartter's syndrome

Answer

Prolonged use of furosemide

Answer

Hyperoxaluria

Question 2

A 4-year-old girl presented with urinary infection caused by E. coli, pus cells in the urine, dilation of the left ureter with hydroureter, and a micturating cystourethrogram showing a filling defect in the bladder. What is the likely diagnosis?

Accepted Answer

Ureterocele (a cystic lesion in the ureter)

Answer

Sacrococcygeal teratoma (a congenital tumor)

Answer

Posterior urethral valves (a condition in males)

Answer

Vesicoureteral reflux (urine backflow into the ureters)

Nephrology — MCQs

Nephrology — MCQs

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